avimux: Add support for >2 raw audio channels

For this case write a WAVEFORMATEXTENSIBLE header and also reorder the
raw audio channels to the AVI channel order if needed.

gst/avi/gstavimux.c

@@ -159,7 +159,7 @@ static GstStaticPadTemplate audio_sink_factory =
     GST_STATIC_CAPS ("audio/x-raw, "
         "format = (string) { U8, S16LE, S24LE, S32LE }, "
         "rate = (int) [ 1000, 96000 ], "
-        "channels = (int) [ 1, 2 ]; "
+        "channels = (int) [ 1, 65535 ]; "
         "audio/mpeg, "
         "mpegversion = (int) 1, "
         "layer = (int) [ 1, 3 ], "
@@ -747,6 +747,69 @@ gst_avi_mux_audsink_set_fields (GstAviMux * avimux, GstAviAudioPad * avipad)
   }
 }
 
+/* Taken from wavenc */
+static guint64
+gstmask_to_wavmask (guint64 gstmask, GstAudioChannelPosition * pos)
+{
+  const GstAudioChannelPosition valid_pos =
+      GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT |
+      GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT |
+      GST_AUDIO_CHANNEL_POSITION_FRONT_CENTER |
+      GST_AUDIO_CHANNEL_POSITION_LFE1 |
+      GST_AUDIO_CHANNEL_POSITION_REAR_LEFT |
+      GST_AUDIO_CHANNEL_POSITION_REAR_RIGHT |
+      GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT_OF_CENTER |
+      GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT_OF_CENTER |
+      GST_AUDIO_CHANNEL_POSITION_REAR_CENTER |
+      GST_AUDIO_CHANNEL_POSITION_SIDE_LEFT |
+      GST_AUDIO_CHANNEL_POSITION_SIDE_RIGHT |
+      GST_AUDIO_CHANNEL_POSITION_TOP_CENTER |
+      GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_LEFT |
+      GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_CENTER |
+      GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_RIGHT |
+      GST_AUDIO_CHANNEL_POSITION_TOP_REAR_LEFT |
+      GST_AUDIO_CHANNEL_POSITION_TOP_REAR_CENTER |
+      GST_AUDIO_CHANNEL_POSITION_TOP_REAR_RIGHT;
+
+  const GstAudioChannelPosition wav_pos[] = {
+    GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT,
+    GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT,
+    GST_AUDIO_CHANNEL_POSITION_FRONT_CENTER,
+    GST_AUDIO_CHANNEL_POSITION_LFE1,
+    GST_AUDIO_CHANNEL_POSITION_REAR_LEFT,
+    GST_AUDIO_CHANNEL_POSITION_REAR_RIGHT,
+    GST_AUDIO_CHANNEL_POSITION_FRONT_LEFT_OF_CENTER,
+    GST_AUDIO_CHANNEL_POSITION_FRONT_RIGHT_OF_CENTER,
+    GST_AUDIO_CHANNEL_POSITION_REAR_CENTER,
+    GST_AUDIO_CHANNEL_POSITION_SIDE_LEFT,
+    GST_AUDIO_CHANNEL_POSITION_SIDE_RIGHT,
+    GST_AUDIO_CHANNEL_POSITION_TOP_CENTER,
+    GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_LEFT,
+    GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_CENTER,
+    GST_AUDIO_CHANNEL_POSITION_TOP_FRONT_RIGHT,
+    GST_AUDIO_CHANNEL_POSITION_TOP_REAR_LEFT,
+    GST_AUDIO_CHANNEL_POSITION_TOP_REAR_CENTER,
+    GST_AUDIO_CHANNEL_POSITION_TOP_REAR_RIGHT,
+  };
+  int k;
+  int chan = 0;
+  guint64 ret = 0;
+  guint64 mask = 1;
+
+  if (gstmask == 0 || ((gstmask & ~valid_pos) != 0))
+    return 0;
+
+  for (k = 0; k < G_N_ELEMENTS (wav_pos); ++k) {
+    if (gstmask & (G_GUINT64_CONSTANT (1) << wav_pos[k])) {
+      ret |= mask;
+      pos[chan++] = wav_pos[k];
+    }
+    mask <<= 1;
+  }
+
+  return ret;
+}
+
 static gboolean
 gst_avi_mux_audsink_set_caps (GstPad * pad, GstCaps * vscaps)
 {
@@ -795,10 +858,15 @@ gst_avi_mux_audsink_set_caps (GstPad * pad, GstCaps * vscaps)
   if (!strcmp (mimetype, "audio/x-raw")) {
     const gchar *format;
     GstAudioFormat fmt;
+    guint64 channel_mask;
 
     format = gst_structure_get_string (structure, "format");
     fmt = gst_audio_format_from_string (format);
 
+    if (!gst_structure_get (structure, "channel-mask", GST_TYPE_BITMASK,
+            &channel_mask, NULL))
+      channel_mask = gst_audio_channel_get_fallback_mask (channels);
+
     switch (fmt) {
       case GST_AUDIO_FORMAT_U8:
         avipad->auds.blockalign = 8;
@@ -820,11 +888,28 @@ gst_avi_mux_audsink_set_caps (GstPad * pad, GstCaps * vscaps)
         goto refuse_caps;
     }
 
+    avipad->audio_format = fmt;
+
     avipad->auds.format = GST_RIFF_WAVE_FORMAT_PCM;
     /* set some more info straight */
     avipad->auds.blockalign /= 8;
     avipad->auds.blockalign *= avipad->auds.channels;
     avipad->auds.av_bps = avipad->auds.blockalign * avipad->auds.rate;
+
+    if (channels > 2 || (channels == 1 && channel_mask != 0x0)
+        || (channels == 2 && channel_mask != 0x3)) {
+      avipad->write_waveformatex = TRUE;
+      /* The same for now as we don't support e.g. S24_32 */
+      avipad->valid_bits_per_sample = avipad->auds.bits_per_sample;
+      avipad->channel_mask =
+          gstmask_to_wavmask (channel_mask, avipad->wav_positions);
+
+      gst_audio_channel_positions_from_mask (channels, channel_mask,
+          avipad->gst_positions);
+      avipad->needs_reorder =
+          memcmp (avipad->gst_positions, avipad->wav_positions,
+          channels * sizeof (*avipad->gst_positions)) != 0;
+    }
   } else {
     avipad->auds.format = 0;
     /* set some defaults */
@@ -1333,13 +1418,27 @@ gst_avi_mux_riff_get_avi_header (GstAviMux * avimux)
       /* the audio header */
       strf = gst_avi_mux_start_chunk (&bw, "strf", 0);
       /* the actual header */
+      if (audpad->write_waveformatex)
+        hdl &= gst_byte_writer_put_uint16_le (&bw, 0xfffe);
+      else
         hdl &= gst_byte_writer_put_uint16_le (&bw, audpad->auds.format);
       hdl &= gst_byte_writer_put_uint16_le (&bw, audpad->auds.channels);
       hdl &= gst_byte_writer_put_uint32_le (&bw, audpad->auds.rate);
       hdl &= gst_byte_writer_put_uint32_le (&bw, audpad->auds.av_bps);
       hdl &= gst_byte_writer_put_uint16_le (&bw, audpad->auds.blockalign);
       hdl &= gst_byte_writer_put_uint16_le (&bw, audpad->auds.bits_per_sample);
+      if (audpad->write_waveformatex) {
+        hdl &= gst_byte_writer_put_uint16_le (&bw, codec_size + 22);
+        hdl &=
+            gst_byte_writer_put_uint16_le (&bw, audpad->valid_bits_per_sample);
+        hdl &= gst_byte_writer_put_uint32_le (&bw, audpad->channel_mask);
+        hdl &= gst_byte_writer_put_uint32_le (&bw, audpad->auds.format);
+        hdl &= gst_byte_writer_put_uint32_le (&bw, 0x00100000);
+        hdl &= gst_byte_writer_put_uint32_le (&bw, 0xAA000080);
+        hdl &= gst_byte_writer_put_uint32_le (&bw, 0x719B3800);
+      } else {
         hdl &= gst_byte_writer_put_uint16_le (&bw, codec_size);
+      }
       if (audpad->auds_codec_data) {
         gst_buffer_map (audpad->auds_codec_data, &map, GST_MAP_READ);
         hdl &= gst_byte_writer_put_data (&bw, map.data, map.size);
@@ -2070,6 +2169,17 @@ gst_avi_mux_do_buffer (GstAviMux * avimux, GstAviPad * avipad)
     if (gst_avi_mux_is_uncompressed (avipad->hdr.fcc_handler)) {
       data = gst_avi_mux_invert (avipad, data);
     }
+  } else {
+    GstAviAudioPad *audpad = (GstAviAudioPad *) avipad;
+
+    if (audpad->needs_reorder) {
+      data = gst_buffer_make_writable (data);
+      if (!gst_audio_buffer_reorder_channels (data, audpad->audio_format,
+              audpad->auds.channels, audpad->gst_positions,
+              audpad->wav_positions)) {
+        GST_WARNING_OBJECT (avimux, "Could not reorder channels");
+      }
+    }
   }
 
   if (avimux->restart) {

gst/avi/gstavimux.h

@@ -25,6 +25,7 @@
 #include <gst/gst.h>
 #include <gst/base/gstcollectpads.h>
 #include <gst/riff/riff-ids.h>
+#include <gst/audio/audio.h>
 #include "avi-ids.h"
 
 G_BEGIN_DECLS
@@ -114,6 +115,16 @@ typedef struct _GstAviAudioPad {
 
   /* stream format */
   gst_riff_strf_auds auds;
+  /* additional fields for WAVEFORMATEX */
+  gboolean write_waveformatex;
+  guint16 valid_bits_per_sample;
+  guint32 channel_mask;
+
+  /* for raw audio */
+  gboolean needs_reorder;
+  GstAudioFormat audio_format;
+  GstAudioChannelPosition gst_positions[64], wav_positions[64];
+
   /* audio info for bps calculation */
   guint32 audio_size;
   guint64 audio_time;